New SIM not working

a week ago

I've seen lots of people posting the same question. I was randomly send a new purple SIM card but when I put it into my iPhone it says it's not supported? My phone has always been locked to virgin so I'm don't see why the new SIM isn't working?

Also... ever since I put the new SIM in my old one is now not working?! I've seen other people say they had to pay to get their phone unlocked which I'm not doing!!